A conventional wrench includes a handle and an open end which has two jaws and a U-shaped clamping opening is defined between the two jaws. The width of the clamping opening is designed to accommodate a bolt head or a nut and the two jaws clamp two sides of the object by the clamping surfaces thereof. By rotation of the wrench, the nut clamped by the two jaws can be rotated. Nevertheless, after the handle is rotated an angle, the open end has to be removed from the nut and be mounted to the nut again. If there are objects located around the nut, the handle can only be rotated a limited angle. In this situation, the user has to repeatedly mount and remove the open end. This takes a lot of time and affects the efficiency of work.
The present invention intends to provide a wrench having an open end including two jaws. Each jaw includes a clamping portion and a loose portion which is recessed inward from an inside of each jaw. A pushing tongue is located between the two jaws so that the nut can be clamped by the clamping portions by compressing the pushing tongue, and freely rotated when being pushed to the space enclosed by the loose portions by the pushing tongue.